Regarding centrifugal pumps
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The centrifugal pump’s nameplate indicates a head of 50 meters, but after starting the pump, the pressure gauge shows large fluctuations and the pressure does not reach 5 kilograms. The outlet valve is closed, and the pressure gauge reads around 5 kilograms normally. The medium used is 50°C heat transfer oil. Could unstable inlet flow be the cause of this issue? (Suspected that the plate heat exchanger may be clogged, resulting in insufficient inlet flow.)
Why isn’t anyone replying to me??? Urgent! !
Yes, it’s probably due to blockage at the inlet causing evacuation. Even if the pump fails to reach the designed head, the outlet pressure shouldn’t experience significant fluctuations. Check if Ben vibrates a lot; the vibration will be severe when it’s empty.
The pump is a bit noisy, but not very loud. The pressure gauge readings fluctuated within the range of 2-3 kilograms. At first, I thought there was a leak in the inlet pipeline, but after stopping the pump and releasing pressure, it was found that there was no leak in the inlet pipeline. Therefore, it was concluded that the inlet was blocked, resulting in insufficient flow. However, even with insufficient flow, the pressure shouldn’t fluctuate so much, unless the flow rate is zero. Personally, I think as long as flow enters the pump and is pressurized by the impeller, the pressure should not fluctuate significantly. I now doubt whether there is a problem with the pump itself
A head of 50 meters does not mean that the pressure at the pump outlet is 5 kg/cm2; this depends on the density of the medium as well as the pressure at the pump inlet. It has also been observed that the pump casing or impeller becomes severely corroded, resulting in a significant drop in outlet pressure; however, heat transfer oil should not suffer from such severe corrosion.
It is highly likely that the pump inlet area is blocked； Is there a filter screen at the pump inlet? If there are any, please clarify them. Also, is it possible for the heat transfer oil to contain water, thereby causing vaporization and evacuation?
The resistance at the pump inlet is high; closing the outlet valve a bit tighter may reduce pressure fluctuations
Yes, I checked the density – it’s roughly the same as that of water. The inlet pressure should be at atmospheric pressure; perhaps after the pump is emptied, the average density decreases, which leads to a drop in the pressure indicated by the gauge.
The outlet valve is fully closed, creating a pressure buildup of exactly 5 kilograms
Even with water present, at normal pressure at the inlet, vaporization does not occur; I think the blockage at the inlet is what causes evacuation and large pressure fluctuations